Hydrogen storage alloy and preparation method thereof
Technical Field
The invention belongs to the technical preparation field of alloys. Relates to an alloy and a preparation method thereof, in particular to a hydrogen storage alloy and a preparation method thereof.
Background
Along with the increasing consumption of fossil fuel, the reserves of the fossil fuel are reduced, hydrogen energy is taken as an ideal new energy-containing energy source, is regarded as one of the most potential clean energy sources, is positioned at the beginning of the periodic table of elements, has an atomic number of 1, is in a gaseous state at normal temperature and pressure, is in a liquid state at ultralow temperature and high pressure, and has wide application prospect. However, since hydrogen exists in a gaseous form under ordinary conditions and is flammable and explosive, it presents great difficulties in its storage and transportation. Therefore, how to properly solve the problem of hydrogen storage and transportation becomes a key to the development of hydrogen energy.
The hydrogen storage alloy is used as a novel alloy, is a hot spot of current research, hydrogen enters the hydrogen storage alloy under certain conditions, and generates chemical action with the alloy to generate metal hydride, so that the purposes of hydrogen storage and transportation are achieved; when hydrogen is used, the metal hydride can be heated to carry out the reverse reaction, so that the hydrogen is released; the hydrogen storage alloy has excellent cycle life performance and can be used for large batteries, especially electric vehicles, hybrid electric vehicles, other high-power applications and the like. The current hydrogen storage alloys mainly comprise titanium-based, zirconium-based, iron-based and rare earth-based hydrogen storage alloys.
CN101532102A discloses a rare earth hydrogen storage alloy, the chemical formula of the rare earth hydrogen storage alloy is shown in the specification :Ml1-xDyx(NiaCobAlcMndCueFefSngCrhZni),, wherein x is more than 0 and less than 0.3,2 and less than 4, b is more than 0 and less than 0.3,0.2 and c is more than 0.4,0.2 and less than 0.5, e is more than 0 and less than 0.2, f is more than 0 and less than 0.25, g is more than 0 and less than 0.22,0 and less than 0.18,0 and i is more than 0.28, and M l is mixed rare earth. According to the technical scheme, cu, cr, zn, fe and Sn are used for replacing Co element in the rare earth hydrogen storage alloy, so that the cycle stability of the hydrogen storage alloy can be obviously improved, the Co content in the hydrogen storage alloy is reduced by more than 60% compared with that of a commercial hydrogen storage alloy MlNi 3.55Co0.75Mn0.4Al0.3, the production cost is greatly reduced, but the capacity of the obtained rare earth alloy is small and cannot meet the requirement of high capacity, and the problem of large expansion of the unit cell volume exists in the hydrogen absorption and desorption cycle process.
CN102443730a discloses a hydrogen storage alloy, which is a high entropy alloy and has the molecular formula of Co uFevMnwTixVyZrz, the hydrogen storage alloy is an alloy material without rare earth elements, has a single C14 Laves phase structure, is stable in structure, can have high hydrogen absorption and hydrogen release capacities under normal temperature and normal pressure working environment, and has hydrogen storage capacity at room temperature, and the hydrogen storage alloy provided by the technical scheme can be widely applied to hydrogen storage, heat pumping, hydrogen purification and isotope separation, can be used in the fields of secondary batteries, fuel cells and the like, does not generate polluted gas harmful to the earth, and is a green environment-friendly energy source with great development potential. The Laves phase in the titanium-zirconium hydrogen storage alloy has the advantages of high hydrogen storage capacity, long cycle life and the like, but also has the defects of difficult activation, high price and the like which are difficult to overcome.
CN100513605A discloses a quaternary magnesium-based hydrogen storage alloy, its production method and application, the quaternary magnesium-based hydrogen storage alloy is composed of Mg 1.5-2Al0.02-0.08Ni0.5-1.0A0.05-0.1, wherein a is V, ti, fe, nd, pd, and dispersed nanocrystalline clusters and amorphous clusters are distributed in microstructure. Fully mixing alloy element powder, pressing into a sheet shape, sintering in a vacuum sintering furnace, and crushing, ball milling and screening an obtained alloy sample to obtain alloy powder with granularity less than 25 mu m; weighing a small amount of fine Ni powder, and performing ball milling to obtain nanocrystalline Ni powder; fully mixing Mg 1.5-2Al0.02- 0.08Ni0.5-1.0A0.05-0.1 alloy powder with granularity below 25 mu m, nanocrystalline Ni powder and second-phase active particles, performing high-energy ball milling to obtain an active hydrogen storage alloy material with nanocrystalline and amorphous structures, and activating to obtain a finished product. The finished product has the characteristics of low hydrogen absorption/desorption temperature, stable performance, practicability and low price; the magnesium hydrogen storage alloy has rich resources and high hydrogen storage capacity, but the alloy has poor hydrogen absorption/desorption kinetics and certain defects.
In this regard, the invention provides a hydrogen storage alloy and a preparation method thereof, which improves the hydrogen storage capacity, reduces the production cost and has the characteristic of easy activation.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a hydrogen storage alloy and a preparation method thereof, which improve the hydrogen storage capacity, optimize the hydrogen storage performance and reduce the production cost.
To achieve the purpose, the invention adopts the following technical scheme:
In a first aspect, the present invention provides a hydrogen storage alloy having a raw material composition comprising Ti, cr, mo and M; m is Ce and/or Ca;
The hydrogen storage alloy comprises the following components in parts by mole:
the hydrogen storage alloy is obtained by optimally designing the raw material components, wherein M is Ce and/or Ca and is metal easy to hydrogenate, and the activation performance of the hydrogen storage alloy can be obviously improved, so that the problem of difficult activation of the hydrogen storage alloy is solved.
Preferably, the crystal structure of the hydrogen storage alloy is a body centered cubic structure.
In the composition of the hydrogen storage alloy, the mole fraction of Ti is 3.5 to 5 parts, for example, 3.5 parts, 3.8 parts, 4 parts, 4.3 parts, 4.5 parts, 4.8 parts or 5 parts, but not limited to the recited values, and other non-recited values in the numerical range are equally applicable.
The composition of the hydrogen absorbing alloy is 4.5 to 6 parts by mole of Cr, for example, 4.5 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts or 6 parts, but not limited to the recited values, and other non-recited values in the numerical range are equally applicable.
In the composition of the hydrogen storage alloy, the mole fraction of Mo is 0.7 to 1.3 parts, for example, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts or 1.3 parts, but not limited to the recited values, and other non-recited values in the numerical range are equally applicable.
In the composition of the hydrogen absorbing alloy, the molar fraction of M is 0.1 to 0.5 part, for example, 0.1 part, 0.15 part, 0.2 part, 0.25 part, 0.3 part, 0.35 part, 0.4 part or 0.5 part, but not limited to the recited values, and other non-recited values in the numerical range are equally applicable.
Preferably, the crystal structure of the hydrogen storage alloy is a body centered cubic structure.
In a second aspect, the present invention provides a method for producing a hydrogen occluding alloy as recited in the first aspect, comprising the steps of:
(1) Mixing, tabletting and smelting raw materials in the formula amount to obtain an as-cast alloy;
(2) Annealing, quenching and post-treatment are carried out on the as-cast alloy obtained in the step (1) to obtain the hydrogen storage alloy;
The annealing temperature in the step (2) is 1350-1450 ℃.
The invention performs phase regulation and control on the formula raw materials by smelting, annealing and other methods, improves the capacity of the obtained hydrogen storage alloy, optimizes the cycle performance of the hydrogen storage alloy, and has the characteristics of simple preparation method and low cost.
Illustratively, the tabletting of step (1) of the present invention results in a mixed metal ingot.
In the invention, the formula raw materials are subjected to tabletting treatment, so that the activation difficulty of the obtained hydrogen storage alloy can be reduced; because the melting point of Mo in the raw material is higher and the melting point of M is lower, the metal with low melting point is easy to volatilize by directly smelting the raw material, so that M cannot play the role of the hydrogen storage alloy, and the problem of difficult activation cannot be solved.
The annealing temperature in step (2) is 1350-1450 ℃, and may be 1350 ℃, 1380 ℃, 1400 ℃, 1430 ℃, or 1450 ℃, for example, but is not limited to the values recited, and other values not recited in the numerical range are equally applicable. The annealing temperature in the step (2) is controlled within the range of 1350-1450 ℃, which is beneficial to improving the capacity of the obtained hydrogen storage alloy and optimizing the hydrogen storage performance; when the annealing temperature is lower than 1350 ℃, the stress reduction amount of the obtained hydrogen storage alloy is small, so that the hydrogen absorption and desorption platform of the obtained alloy is inclined, and the hydrogen absorption amount and the effective hydrogen desorption amount are reduced; when the annealing temperature is higher than 1450 ℃, the as-cast alloy obtained in step (1) is easily oxidized, resulting in a decrease in the performance of the resulting hydrogen storage alloy.
Preferably, the annealing time in step (2) is 1-8min, for example, 1min, 2min, 3min, 4min, 5min, 6min, 7min or 8min, but not limited to the recited values, and other non-recited values in the range of values are equally applicable.
Preferably, the temperature rising rate of the annealing in the step (2) is 5-10 ℃/min, for example, 5 ℃/min, 6 ℃/min, 7 ℃/min, 8 ℃/min, 9 ℃/min or 10 ℃/min, but the annealing is not limited to the listed values, and other non-listed values in the range of values are equally applicable.
Preferably, the pressure of the tablet in step (1) is 5-20MPa, for example, 5MPa, 8MPa, 10MPa, 13MPa, 15MPa, 18MPa or 20MPa, but not limited to the values listed, and other values not listed in the numerical range are equally applicable.
Preferably, the number of times of smelting in step (1) is 3-5, and may be 3 times, 4 times or 5 times, for example.
In the invention, because the melting point of Mo in the raw material is higher, 3-5 times of smelting are needed to realize the alloying process of the multi-element alloy; when the number of times of melting is 1 or 2, there is a variation in melting, resulting in deterioration of the hydrogen storage performance of the resulting hydrogen storage alloy; when the number of times of smelting is more than 5, the hydrogen storage performance is deteriorated due to the severe volatilization of the low melting point metal M, and the energy waste is serious.
Preferably, the smelting current in the step (1) is 100-300A, for example, 100A, 150A, 200A, 250A or 300A, but not limited to the recited values, and other non-recited values in the range of values are equally applicable.
Preferably, the smelting time in step (1) is 10-20s, for example, 10s, 12s, 14s, 16s, 18s or 20s, but not limited to the recited values, and other non-recited values in the range of values are equally applicable.
Preferably, the as-cast alloy obtained in the step (1) is subjected to tube sealing treatment before annealing in the step (2): and (3) placing the as-cast alloy obtained in the step (1) into a quartz tube, vacuumizing, and sealing the tube under an inert atmosphere.
Preferably, during the tube sealing treatment, the surface of the cast alloy obtained in the step (1) is coated with tantalum sheets.
Preferably, the number of times of vacuum pumping is 2-4 times, for example, 2 times, 3 times or 4 times.
Preferably, the inert atmosphere comprises nitrogen and/or argon.
Preferably, the relative pressure of the inert atmosphere is 0.4-0.6atm, which may be, for example, 0.4atm, 0.45atm, 0.5atm, 0.55atm or 0.6atm, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
Preferably, the quenching of step (2) comprises water quenching.
Preferably, the temperature of the water quench is room temperature.
The room temperature of the present invention may be 15 to 25℃in the temperature range of 15℃and 18℃and 20℃and 21℃and 24℃or 25℃for example, but the present invention is not limited to the values recited, and other values not recited in the numerical range are applicable.
Preferably, the post-treatment of step (2) comprises grinding and crushing.
Preferably, the average particle diameter of the hydrogen absorbing alloy obtained after crushing is 80 to 200 mesh, for example, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh or 200 mesh, but not limited to the recited values, and other values in the numerical range are equally applicable.
Preferably, the hydrogen storage alloy obtained in step (2) has a smaller crystal constant than the as-cast alloy obtained in step (1).
Preferably, the as-cast alloy obtained in step (1) has a crystal constant a of 0.303-0.306nm, for example, 0.303nm, 0.304nm, 0.305nm or 0.306nm, but not limited to the values recited, and other values not recited in the numerical range are equally applicable.
Preferably, the hydrogen storage alloy obtained in step (2) has a crystal constant a of 0.302 to 0.305nm, for example, 0.302nm, 0.303nm, 0.304nm or 0.305nm, but not limited to the values recited, and other values not recited in the numerical range are equally applicable.
As a preferred technical scheme of the preparation method according to the second aspect of the present invention, the preparation method comprises the following steps:
(1) Mixing the raw materials according to the formula, tabletting under the pressure of 5-20MPa, and smelting 3-5 times under the current of 100-300A to obtain an as-cast alloy with the crystal constant a of 0.303-0.306 nm;
(2) Coating tantalum sheets on the surface of the as-cast alloy obtained in the step (1), placing the tantalum sheets in a quartz tube, vacuumizing for 3-5 times, sealing the tube under an inert atmosphere of 0.4-0.6atm, annealing for 1-8min at a heating rate of 5-10 ℃/min to 1350-1450 ℃, and carrying out water quenching and post-treatment to obtain the hydrogen storage alloy with a crystal constant a of 0.302-0.305 nm;
The hydrogen storage alloy comprises the following components in parts by mole: 3.5-5 parts of Ti; cr 4.5-6 parts; 0.7-1.3 parts of Mo; 0.1-0.5 part of M, wherein M is Ce and/or Ca.
Compared with the prior art, the invention has the beneficial effects that:
According to the invention, the hydrogen storage alloy is obtained by optimally designing the raw material components, wherein M is Ce and/or Ca and is metal easy to hydrogenate, so that the activation performance of the hydrogen storage alloy can be remarkably improved, and the problem of difficult activation of the hydrogen storage alloy is solved; the formula raw materials are subjected to phase regulation and control by smelting, annealing and other methods, so that the capacity of the obtained hydrogen storage alloy is improved, the cycle performance of the hydrogen storage alloy is optimized, and the hydrogen storage alloy has the characteristics of simple preparation method and low cost.
Drawings
FIG. 1 is a graph showing the normal-temperature activation performance of the hydrogen occluding alloys obtained in example 1, example 4, comparative example 1 and comparative example 2;
FIG. 2 is a comparison of PCT curves of hydrogen occluding alloys obtained in example 1, example 4 and comparative example 3.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
The embodiment provides a preparation method of a hydrogen storage alloy, which comprises the following steps:
(1) Mixing Ti, cr, mo and Ce according to the formula, tabletting under the pressure of 10MPa, smelting for 4 times by adopting an electric arc furnace under the condition of 120A current and the vacuum degree of 0.5atm for 20s to obtain an as-cast alloy with the crystal constant a of 0.305 nm;
(2) Coating tantalum sheets on the surface of the as-cast alloy obtained in the step (1), placing the tantalum sheets in a quartz tube, vacuumizing for 4 times, sealing the tube under an inert atmosphere of 0.4atm, annealing for 2min at a heating rate of 6 ℃/min to 1400 ℃, and performing water quenching, polishing and crushing to obtain the hydrogen storage alloy with the average particle size of 100 meshes; the crystal constant a of the obtained hydrogen storage alloy is 0.304nm;
The hydrogen storage alloy comprises the following components in parts by mole: 4 parts of Ti; cr 5 parts; mo 1 parts; ce 0.2 parts.
Example 2
The embodiment provides a preparation method of a hydrogen storage alloy, which comprises the following steps:
(1) Mixing Ti, cr, mo and Ca according to the formula, tabletting under the pressure of 5MPa, and smelting 3 times by adopting an electric arc furnace under the condition of current of 100A and vacuum degree of 0.5atm for 10s to obtain an as-cast alloy;
(2) Coating tantalum sheets on the surface of the as-cast alloy obtained in the step (1), placing the tantalum sheets in a quartz tube, vacuumizing for 2 times, sealing the tube under an inert atmosphere of 0.6atm, annealing for 8min at a heating rate of 5 ℃/min to 1350 ℃, and carrying out water quenching, polishing and crushing to obtain the hydrogen storage alloy with the average particle size of 80 meshes;
The hydrogen storage alloy comprises the following components in parts by mole: 3.5 parts of Ti; cr 6 parts; mo 1 parts; ca 0.5 part.
Example 3
The embodiment provides a preparation method of a hydrogen storage alloy, which comprises the following steps:
(1) Mixing Ti, cr, mo and Ce according to the formula, tabletting under the pressure of 20MPa, and smelting for 5 times by adopting an electric arc furnace under the condition of 300A of current and 0.5atm of vacuum degree for 15s to obtain an as-cast alloy;
(2) Coating tantalum sheets on the surface of the as-cast alloy obtained in the step (1), placing the tantalum sheets in a quartz tube, vacuumizing for 3 times, sealing the tube under an inert atmosphere of 0.4atm, annealing for 1min at a heating rate of 10 ℃/min to 1450 ℃, and performing water quenching, polishing and crushing to obtain the hydrogen storage alloy with the average particle size of 200 meshes;
The hydrogen storage alloy comprises the following components in parts by mole: 3.5 parts of Ti; cr 6 parts; mo 1 parts; ca 0.5 part.
Example 4
The present embodiment provides a method for producing a hydrogen occluding alloy, in which the composition except for the hydrogen occluding alloy includes 3.8 parts of Ti; cr 5 parts; mo 1.2 parts; the procedure of example 1 was repeated except that 0.5 part of Ca was used.
Example 5
This example provides a method for producing a hydrogen occluding alloy, which is the same as in example 4 except that the number of times of melting in step (1) is 2.
Example 6
This example provides a method for producing a hydrogen occluding alloy, which is the same as in example 4 except that the number of times of melting in step (1) is 7.
Example 7
This example provides a method for producing a hydrogen occluding alloy, which is the same as in example 1 except that the relative pressure of the inert atmosphere at the time of the tube sealing treatment in step (2) is 1 atm.
Example 8
This example provides a method for producing a hydrogen occluding alloy, which is the same as in example 1 except that the annealing time in step (2) is 1 h.
Comparative example 1
This comparative example provides a production method of a hydrogen occluding alloy in which the same as in example 1 was conducted except that the composition of the hydrogen occluding alloy did not contain a Ce source.
Comparative example 2
This comparative example provides a method for producing a hydrogen occluding alloy, which is the same as in example 1 except that the raw materials of the formulation amount after the mixing in step (1) are directly melted without being subjected to tabletting.
Comparative example 3
This comparative example provides a method for producing a hydrogen occluding alloy, which is the same as in example 1 except that the annealing temperature in step (2) is 1000 ℃.
Comparative example 4
This comparative example provides a method for producing a hydrogen occluding alloy, which is the same as in example 1 except that the annealing temperature in step (2) is 1200 ℃.
Comparative example 5
This comparative example provides a method for producing a hydrogen occluding alloy, which is the same as in example 1 except that the annealing temperature in step (2) is 1500 ℃.
Performance testing
The hydrogen storage alloys provided in examples 1 to 8 and comparative examples 1 to 5 were subjected to a hydrogen storage performance test at 25℃under a relative pressure of H 2 of 8MPa, and the maximum hydrogen absorption amount, the effective hydrogen release amount and the plateau pressure of the obtained hydrogen storage alloy were tested, and whether the hydrogen storage alloy could be activated at normal temperature or not was tested, with a specific test method being referred to national standard GB/T33291-2016. The results are shown in Table 1.
TABLE 1
As can be seen from examples 1-4, the maximum hydrogen absorption amount of the hydrogen storage alloy can reach 3.6wt%, the effective hydrogen release amount can reach 2.5wt%, the platform pressure is about 0.2MPa, the hydrogen storage performance is excellent, and the normal temperature activation can be realized.
As can be seen from comparison of examples 5, 6 and 4, the melting point of Mo in the raw material is higher, and 3-5 times of smelting are needed to realize the alloying process of the multi-element alloy in the invention; when the number of times of melting is less than 3, there is a variation in melting, resulting in deterioration of the hydrogen storage performance of the resulting hydrogen storage alloy; when the smelting times are higher than 5 times, the hydrogen storage performance is not obviously improved, and the energy waste is serious.
As is clear from a comparison between example 7 and example 1, too high relative pressure of the inert atmosphere during the tube sealing treatment in the invention also affects the hydrogen storage performance, because the annealing temperature is higher, the pressure in the quartz tube is too high, the quartz tube is easy to break, the sample is oxidized during annealing, and the hydrogen storage performance is poor.
As can be seen from a comparison of the embodiment 8 and the embodiment 1, the annealing time is too long to cause new thermal stress, and the phenomena of recrystallization, grain growth and the like may occur, so that the improvement of the hydrogen absorption and desorption platform of the alloy is not obvious, and the maximum hydrogen absorption amount and the effective hydrogen desorption amount are affected.
As can be seen from comparison of comparative example 1 and example 1, the hydrogen storage alloy is obtained by optimally designing the raw material components, wherein M is Ce and/or Ca, and the M is metal which is easy to hydrogenate, so that the activation performance of the hydrogen storage alloy can be obviously improved, and the problem of difficult activation of the hydrogen storage alloy is solved; when the metal M is not added, the resulting hydrogen storage alloy cannot be activated at normal temperature.
As can be seen from the comparison of the comparative example 2 and the example 1, the invention can reduce the activation difficulty of the obtained hydrogen storage alloy by tabletting the formula raw materials; because the melting point of Mo in the raw material is higher and the melting point of M is lower, the metal with low melting point is easy to volatilize by directly smelting the raw material, so that M cannot play the role of the hydrogen storage alloy, and the problem of difficult activation cannot be solved.
Fig. 1 is a graph showing the normal temperature activation performance of the hydrogen occluding alloys obtained in example 1, example 4, comparative example 1 and comparative example 2, and it can be seen that the hydrogen occluding alloys obtained in example 1 and example 4 can be activated at normal temperature after being tabletted and M is added during the preparation process, whereas the normal temperature activation cannot be achieved without adding M to the raw material in comparative example 1, and the normal temperature activation cannot be achieved without tableting in comparative example 2.
As can be seen from comparison of comparative examples 3 to 5 with example 1, as the annealing temperature decreases, when the annealing temperature is lower than 1350 ℃, the stress of the obtained hydrogen storage alloy decreases less, so that the hydrogen absorption and desorption platforms of the obtained alloy are inclined, resulting in a decrease in both the maximum hydrogen absorption amount and the effective hydrogen desorption amount; when the annealing temperature is higher than 1450 ℃, the temperature resistance limit of the quartz tube is exceeded, and the as-cast alloy obtained in the step (1) is easily oxidized, so that the obtained hydrogen storage alloy has no performance. Therefore, the annealing temperature in the step (2) is controlled within the range of 1350-1450 ℃, which is beneficial to improving the capacity of the obtained hydrogen storage alloy and optimizing the hydrogen storage performance.
Fig. 2 is a comparison of PCT curves of the hydrogen storage alloys obtained in example 1, example 4 and comparative example 3, and it can be seen that the hydrogen storage alloys provided in example 1 and example 4 have a plateau pressure of about 0.2MPa, whereas the hydrogen storage alloys obtained in comparative example 3 have a lower annealing temperature, and the alloy stress is less significant, so that the hydrogen absorption and desorption plateau of the obtained hydrogen storage alloy is still inclined, thereby reducing the maximum hydrogen absorption and effective hydrogen desorption.
In summary, the invention provides a hydrogen storage alloy and a preparation method thereof, and the hydrogen storage alloy is obtained by optimally designing all raw material components, wherein M is Ce and/or Ca, and the M is metal easy to hydrogenate, so that the activation performance of the hydrogen storage alloy can be obviously improved, and the problem of difficult activation of the hydrogen storage alloy is solved; the formula raw materials are subjected to phase regulation and control by smelting, annealing and other methods, so that the capacity of the obtained hydrogen storage alloy is improved, the cycle performance of the hydrogen storage alloy is optimized, and the hydrogen storage alloy has the characteristics of simple preparation method and low cost.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that fall within the technical scope of the present invention disclosed herein are within the scope of the present invention.